Mourners lined up early Saturday to pay their respects to a New York City police officer shot to death while sitting in a patrol car in Brooklyn last month.

Uniformed police officers from across the country joined family, friends and loved ones for the wake of Officer Wenjian Liu at the Aievoli Funeral Home in the Bensonhurst section of Brooklyn. The wake is scheduled to last until 9 p.m

NYPD Police Commissioner William Bratton arrived just before 1 p.m. and was joined by New York City Mayor Bill de Blasio. The two entered the funeral home together.

On Sunday, Liu’s funeral — at the same funeral home — will include a Chinese ceremony led by Buddhist monks followed by a traditional police ceremony with eulogies led by a chaplain. Burial will follow at Cypress Hills Cemetery.

Liu, 32, and his partner Rafael Ramos, 40, were ambushed on Dec. 20. Ramos’ funeral last weekend drew whose funeral drew more than 10,000 officers.

The cops were targeted by Ismaaiyl Brinsley, 28, who said in social media posts that he intended to kill police to avenge the deaths of two unarmed black men, Michael Brown of Ferguson, Mo., and Eric Garner of Staten Island, N.Y. Grand jury decisions not to indict the police officers involved in those two cases sparked nationwide protests.

Liu, 32, had served with the NYPD for 7 1/2 years and was assigned to the 84th Precinct. He is survived by his wife of two months. At Ramos’ funeral, Police Commissioner William Bratton promoted both Ramos and Liu from patrolmen to the rank of detective first grade.

The city closed streets around the Aievoli Funeral Home to accommodate mourners for wake, the city said on its website. The funeral home will broadcast the services on large outdoor screens for overflow crowds.

JetBlue, which offered free flights to New York for police officers around the USA who want to attend the funeral, committed to flying 1,146 officers to the services, spokesman Morgan Johnston said. The airline flew 845 officers to Ramos’ funeral last weekend, he said.

At last week’s funeral for Ramos, hundreds of police officers turned their backs on Mayor de Blasio when he spoke. De Blasio is also scheduled to speak at Liu’s funeral Sunday.

Police leaders said de Blasio showed disrespect for cops in statements he has made in support of nationwide protests against police brutality and racial profiling. In controversial comments, police officials have said de Blasio’s remarks may have even encouraged violence against officers.

Since Ramos and Liu were killed, police in New York have investigated at least 70 threats made against officers, and more than a dozen people have been arrested.

Commissioner Bratton said in a statement Friday the act of officers turning their backs “stole the valor, honor, and attention that rightfully belonged to the memory of Detective Rafael Ramos’s life and sacrifice.”

“I issue no mandates, and I make no threats of discipline, but I remind you that when you don the uniform of this department, you are bound by the tradition, honor and decency that go with it,” Bratton said. “A hero’s funeral is about grieving, not grievance.”

Contributing: The Associated Press